﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace 求圆面积
{
    class Program
    {
        static void Main(string[] args)
        {
            const double PI = 3.14;
            Console.WriteLine("请写出要求圆的半径");
            
            double r = double.Parse(Console.ReadLine());//我要对半径的数据类型进行更改

            double squre = r * r * PI;
            System.Console.WriteLine("面积是{0}",squre);
            Console.ReadKey();
        }
    }
}
